textproduct: Quad Cities

KEY MESSAGES

- Thunderstorms are expected to hold off until mid to late evening tonight as the main severe weather threat remains tied to the cold front position well to our west this afternoon.

- A mature to dissipating squall line of storms is expected to move towards our western counties later this evening, and begin to dissipate/break up as it moves eastward.

- Cooler weather is expected for the mid to late week, with increasing rain chances Thursday night through Friday.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 200 PM CDT Mon May 18 2026

Two areas of scattered storms and rain moved through the area early this morning, resulting in some beneficial rainfall, and extensive cloud cover over the area through this morning. The cloud cover has resulted in far less instability available for any storms over eastern Iowa this afternoon, while Illinois and Missouri continues to see over-running rains just south of our counties from the expansion of the early morning storm cluster that impacted our CWA today. This vast area of stable air should keep any prefrontal storms from forming in our CWA this afternoon and early evening.

Farther west, a different story exists. Strong heat and convergence is over eastern KS, feeding into a triple point just north of Salina KS. This rather obvious spot with strongly backed winds, ample CAPE, and focusing mechanism supports supercell growth in eastern KS, southeast NE, northwest MO, and far southwest Iowa this afternoon through mid evening, as is outlined by SPC for a Moderate and Enhanced Risk. That Enh risk previously included eastern Iowa, but has been shifted west due to the late arrival time, and expectation of instability waning overnight.

Various CAMs agree nearly all agree on supercells spreading east and northeast into southwest Iowa this evening, merging into a line, with bowing segments and damaging winds as is moves towards south southwest Iowa and MO. From this point going forward, convection appears to show the highest potential to split north and south, with the northern side moving towards Wisconsin and MN following the best shear and forcing, while the most significant severe weather will drop southeast from its initiation point in eastern KS to central and possibly northern MO with a significant wind threat, as well as heavy rain in MO. For our CWA, that could leave us out of the threat for severe weather, however given some threat for an organized line of storms on the northern flank of the Missouri activity, we could see a gusty squall line move from west to east over the area, as shear values will be sufficient for this to happen. In fact, if it does happen, 0-1km shear vectors could allow for some QLCS tornado potential as damaging meso vorts along the line. (if we get a coherent line overnight).

Activity will be decaying regarding QPF overnight, with most rainfall expected in our southern counties once again. By early Tuesday morning, any rain will be quickly exiting our southeast CWA with a cloudy cool morning in place. Northwest winds will bring in plenty CAA Tuesday and Tuesday evening, as temperatures fall from highs in the low 60s west to mid 70s east to the 40s by mid evening Tuesday.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 200 PM CDT Mon May 18 2026

Cool high pressure looks to move in for Tuesday night through Wednesday night, resulting in lows in the 40s, but highs in the mid to upper 60s. This rather nice weather will give way to potential rain and clouds for Thursday afternoon through Friday as there is a growing signal for an upper low/deep trof passing through the Midwest in that time frame. Pops are now increased to likely (55- 70%) for Thursday night and Friday, with some thunder possible. The clouds and showers will hold temperatures down into the 60s both days, before a warm up into the 70s and 80s spreads in for the weekend.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1228 PM CDT Mon May 18 2026

Some MVFR to VFR conditions lingering today behind earlier convection, with an expectation MVFR to low VFR deck to develop ahead of the next round of precipitation to move into late this evening/tonight. Winds have been some variable with weak influences lingering from last night's storms, but a boundary in place from southwest to northeast across Iowa to the northwest of the area that should allow for southerly flow to southwesterly flow to setup by this evening with that boundary to move through behind the storm's late tonight with winds to shift around to the west to northwest for Tuesday. Expect a band of showers/storms to spread across the area from the west/southwest late this evening into the overnight hours, with low IFR to MVFR CIGS developing behind the precipitation and boundary moving through the region into Tuesday morning.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.